Control device



June 11, 1940.

A. w. SHEPHERD CONTROL DEVICE Filed June '13, 1938 IN VEN TOR. ALFRED WSHEPHERD I v ATTORNEYS. v

Patented June 11 1940 UNITED STATES PATENT OFFICE 8 Claims.

In the operation of devices such as oil or stoker fired steam boilers,it is customary to provide safety devices in the nature of switchcontrols. These are intended to cut oil the operation of the oil burnermotor or stoker on low water conditions in the boiler. It is alsodesirable to provide a control wherein on low water conditions, waterwill be automatically fed to the boiler until a proper water levelcondition has been reached in the boiler, whereupon water supply isautomatically cut off.

Difllculty has been experienced with certain devices now in commercialuse due to the fact that sediment accumulating in the apparatus makes itinoperative.

The present invention has for its object the provision of a simple andimproved construction for control devices of this character which willnot be subject to the disadvantages and defects 3 of previous devices.

A further object resides in the provision of a control device whereinthe float which controls the operation is disposed within the free waterspace of the boiler in such a relation that it will u be washed by theturbulence of the water in the boiler whereby sediment will be preventedfrom accumulating thereon or thereunder as heretofore.

A further object of the present invention re- 30 sides in the provisionof a control device wherein the operating devices for the switchingmeans and the dampening devices therefor are disposed in a liquidcontaining chamber which is separate from the boiler to the general endthat such de- 35 vices be kept clear of sediment accumulations.

Further and other objects of the present invention will be hereinafterset forth in the accompanying specification and claims and shown in thedrawing which shows by way of illustration a 40 preferred embodiment andthe principle thereof and what I now consider to be the best mode inwhich I have contemplated of applying that principle. Other embodimentsof the invention employing the same or equivalent principle may be 45used and structural changes made as desired by those skilled in the artwithout departing from the present invention and within the spirit ofthe appended claims.

In the drawing:

50 Figure l is a sectional view of one embodiment of the invention;

Fig. 2 is a detail view taken on line 2-2 of Fig. 1;

Fig.3 is a view similar to Fig. 1 with a different 55 embodiment of theinvention;

Fig. 4 is a plan view of the dampening paddle. The view is substantiallya cross-section taken on line 4-4 of Fig. 3; and

Fig. 5 is a diagrammatic view of the electrical circuits of the controldevice.

Generally, according to the present invention, in lieu of providing afloat which is disposed with in the boiler and shielded by baffling soas not to be subject to the surging of the water in the boiler asheretofore, a float construction is provided 10 wherein the float isdirectly open to the boiler so as to be directly subject to the surgingof water within the boiler. In this way the float itself and associatedparts in contact with the boiler water are maintained in cleancondition, being 16 constantly freed of accumulation of sediment bythemovement of the water within the boiler.

To prevent oscillation of the float and associated control mechanism,there is provided a dampening chamber which is separate from the 20boiler. Within this chamber there is provided a suitable liquiddampening medium such as antifreeze solution or lubricating oil. Theoperating connections from the float extend through this dampeningchamber and within the dampening chamber there is a dampening devicesuch as a paddle which dampens oscillations-of the float controlledmechanism. The switch mechanisms are preferably disposed exteriorly ofthe dampening chamber and such switch mechanisms may be eithermechanically or magnetically operated.

With such form and construction the devices do not become inoperativedue to accumulation of sediment. Sediment is prevented from reaching theoperating connections extending from the float to the switch.

The sealed liquid filled dampening chamber being sealed off from theboiler cannot receive any accumulation of sediment which would interferewith the proper operation of the movable parts of the device. The deviceis also provided with a switch chamber and there may also be the usualknockout box in proximity to the switch chamber.

Referring to Fig. 1, in more detail in this embodiment, ID is an annularshell threaded at one end at H to fit a tapped opening in the boilerwall l2 at about the normal water line. Secured in any manner as bysoldering to the end of the shell is an annular disc 13 which has inturn sealed to it a flexible bellows I4 which in turn is scaled to thehollow float 15. The other end of the shell i0 is sealed off by aclosure plate I6 of non-magnetic material. The space I! within anddefined by parts l0, l3, l4, l5 and u i6 is filled with any suitableliquid, such as lubricating oil or an anti-freezing liquid. The liquidmay be introduced byremoving a plug 33. This space is the dampeningchamber of the device and within such chamber there are provided switchoperating connections and a dampening paddle. In the form shown in Figs.1 and 2, such switch operating connections include a lever l8 connectedto the float and pivoted at I! to a bracket 20 carried by disc IS. Theflexible bellows permit movement of the float from upper to lowerposition. Such movement is imparted to the operating connections.Suitably attached to the lever I8 is a paddle 21. Such paddle may havethe general configuration of the paddle 2|a of Fig. 4. The right handend of lever 18 carries a small permanent magnet 22. Suitably fixed tothe end of the shell I is a cup-shaped stamping 23 carrying a dividingpartition 24 of insulating material. The space to the left of thispartition is the switch chamber and the space to the right is theconnection chamber. The shell 23 may be provided with the customaryknockouts to permit flexible cables to be entered into the connectionchamber. The switch may be of any desired form. For example, it maycomprise a pair of contacts 25 normally closed and adapted to be openedwhen the magnet 22 is in upper position upon the float l reaching lowerposition (low water cutoff position). With the float in other positionsthe contacts 25 remain closed. For opening the contacts, there may beprovided a pivoted armature member 26 pivoted upon a bracket supportedby the plate 24. This armature member is provided with an insulatedcontact operating pin 21. It will be understood that when magnet 22 isin the upper dotted line position, the armature 28 will be attracted andthe pin 21 will open the normally closed contacts 25.

The switch also comprises another pair of contacts 28 normally closedand adapted to be opened by an insulating pin 29 upon an armature member30, by and upon the attraction of the armature when the magnet 22 is inlower position with the float in upper position (high water cutoffposition).

As diagrammatically indicated in Fig. 5, the normally closed contacts 25are in the circuit of the oil burner or stoker motor M whereas thecontacts 28 are in the circuit of a solenoid 3i adapted to operate avalve. With the solenoid 3| energized, the valve is maintained open, butwhen the solenoid is de-energized, i. e., upon opening of contacts 28with the float IS in upper position the valve is closed and feed watersupply to the boiler is closed.

Referring now to the embodiment of the invention shown in Fig. 3, inthis form, direct mechanical action is provided for actuating the,

switch. The contacts 25 and 28 are replaced by the usual mercuryswitches designated 25a and 28a. Such switches are actuated from anintermediate lever i8b which has a pin and slot connection to lever l8a.Lever |8a is mounted and connected to the float IS in a similar mannerto lever l8 of Fig. 1 and lever 18b has a pivoted mounting in a bracketcarried by a disc 13a which is sealed to the shell and to a bellows Hawhich bellows in turn is sealed to a disc 32 which in turn is sealed tothe end of the lever IBb. A dampening paddle 2Ia is provided attached tolever We.

The operation of the device shown in Fig. 3 will be readily understood.With the float I5 down in low water position, contacts 25a are open.With the float I5 in extreme upper position, high water position, switch28a is operated to open the circuit.

When installed in a boiler, the operation of either embodiment issubstantially the same for circuit controlling purposes. If the waterlevel in the boiler reaches a too low condition, contacts 25 or 25a willopen the circuit to the oil burner or stoker motor and prevent possibleoverheating and damaging of the boiler.

The water supply valve controlled by solenoid 3| will be kept open atall times when the solenoid is maintained energized with contacts 28 or28a closed. However, when these contacts open, which in the conditionestablished with the float in upper position, the water supply valvewill be allowed to close, thus preventing flooding of the boiler.

Durability and reliability of operation is attained with bothconstructions due to the fact that the float and associated partsexposed to water in the boiler are constantly kept clear of sediment bythe surging of the water in the boiler, which is in free access to thefloat and to such parts. The dampening devices function reliably and byextending the operating connections through the sealed liquid dampeningchamber in the manner shown improved reliability of operation issecured, since their action cannot be interfered with by sedimentaccumulations.

The sealed liquid dampening chamber serves to effectually preventsediment in the boiler water from reaching the operating connections oraccumulating in, around or under them.

With previous devices, shields and bailles were provided adjacent thefloat. These afforded ledges for the accumulation of sediment which intime interfered with float operation. With previous devices, sedimentcould accumulate under and around the operating connections andinterfere with their proper operations. With the improved constructionthese difliculties are obviated and enhanced reliability of operation issecured.

What I claim is:

1. A control device of the character described, with a float adapted fordisposition within a boiler for operation by the water therein and withswitching means controlled by the float, characterized by the fact thatthere is combined with said float and switching means, a sealedstationary dampening chamber containing liquid and horizontally disposedbetween the float and switching means, float moved operating connectionsfor the switching means extending through the liquid in said chamber,said connections having dampening means therefor housed within saidliquid dampening chamber, whereby the movements of the connections aredampened by the contained liquid, said chamber being sealed off from theboiler whereby sediment accumulations are prevented from reaching andimpeding operation of the operating connections.

2. The invention according to claim 1, wherein the operating connectionsto operate the switching means comprise a magnet carried by theoperating means and within the liquid dampening chamber, which magnetinfluence magnetic means without the dampening chamber for actuating theswitching means, said sealed dampening chamber and the liquid thereinserving to prevent sediment in the boiler water reaching and impedingthe operation of the operating con nections and of said magnet.

3. The invention according to claim 1 wherein the switching means isdisposed in a switch chamber outside of said dampening chamber.

4. The invention according to claim 1. wherein the switching meanscomprises switching means mechanically operated by the operatingconnections to the float, said operating connections at one endextending to the float through a flexible bellows which provides aflexible sealing wall for the liquid dampening chamber and saidoperating connections at the other end extending to the mechanicallyoperated switching means, through another flexible bellows which formsanother sealing wall for the liquid dampening chamber.

5. A control device including a shell threaded at one end for insertionin a tapped opening in a boiler wall, a float, means including aflexible bellows to seal one end of said shell to said float and afforda passage for operating connections, partitioning means for the otherend of said shell to provide a sealed stationary chamber containing aliquid dampening medium, a switch supporting chamber, with switchingmeans supported therein and operating connections movably supportedwithin the dampening chamber and connected with the float and havingmeans to operate the switching means and having dampening means movedthereby and cooperating with the liquid to dampen the oscillationsthereof.

6. The invention according to claim 5 wherein the partitioning means forthe other end of the shell, includes a flexible bellows through whichthe operating connections to the switching means extend, said switchingmeans being of the mechanically actuated type for direct operation bysaid operating means.

'7. The invention according to claim 5 wherein the means to operate theswitching means comprises a magnet carried by the operating means andwithin the liquid dampening chamber which magnet through thepartitioning means influences magnetic means for actuating the switchingmeans, said sealed dampening chamber and the liquid therein serving toprevent sediment in the boiler water reaching and impeding the operationof the operating connections and of the said magnet.

8. A control device including a float, switching means for operationthereby, a horizontally disposed stationary sealed liquid filleddampening chamber intermediate said switching means and float, operatingconnections for operating the switching means in said dampening chamberwith connections to the float, extending through a sealing bellows, andpaddle means in said chamber attached to the operating connections, saidfloat being adapted for disposition within a boiler in unshielded freecontact with the water therein for scouring by water surges.

ALFRED W. SHEPHERD.

